An inductor is a type of chip electronic component, and is a representative passive device that may constitute a component in an electronic circuit along with a resistor and a capacitor to remove noise therefrom. In addition, it may be used to configure a resonance circuit for amplifying a signal within a specific frequency band via a combination with a capacitor using electromagnetic characteristics, a filter circuit, and so on.
Recently, the drive towards the miniaturization and thinning of information technology (IT) devices such as communications devices and display devices has accelerated. In accordance with this, research into various miniaturized and thinned devices such as inductors, capacitors, and transistors employed in the IT device has also been continuously conducted. For example, inductors have been rapidly converted into a chip that is miniaturized and able to be automatically mounted on a surface with a high density, and a thin-film type inductor formed by mixing magnetic powder with resin on a coil pattern formed by plating on upper and lower surfaces of a thin insulating substrate has been continuously developed.
The thin-film type inductor may be manufactured by forming a coil pattern on an insulating substrate and then filling an outer portion of the main body with a magnetic material.
A plated area is important to enhance direct current resistance Rdc, an important characteristic of the inductor. To this end, an anisotropic plating scheme of applying high current density to only grow plating layers in a direction above a coil has been applied.
In detail, in a substrate plating procedure for forming a coil of the inductor, a primary pattern plating procedure is performed, and then secondary plating is performed by coating an insulating material such as a solder resist (SR) or a dry film resist (DFR) on a specific portion of the coil.
In general, internal plating layers, which are the plating layers except for an outermost plating layer and an innermost plating layer, have relatively constant plating widths and thicknesses due to adjacent plating layers in opposite directions in the secondary plating procedure after the primary plating.
However, since the outermost plating layer and the innermost plating layer have no adjacent plating layer on one side, plating material may be excessively plated on that side during the secondary plating. Accordingly, in general the outermost and innermost coil conductor patterns have a greater plating width than an inner coil conductor pattern.
In addition, since the outermost plating layer and the innermost plating layer have no adjacent plating layer on one side and a dam such as a solder resist (SR) or a dry film resist (DFR) is disposed, copper ion supply may be insufficient, and thus a plating layer may be slowly grown in a thickness direction such that distribution with a plating thickness of all coil conductor patterns occurs.
Due to the above distribution with the plating thickness, it may be difficult to achieve designed capacity or to achieve direct current Rdc characteristics.